Apparatus for continuously monitoring the process of certain reactions

ABSTRACT

APPARATUS FOR DETERMINING THE PROGRESS OF REACTION BETWEEN REACTANTS WHICH PRODUCE A PRODUCT WHOSE MISCIBILITY IN A SOLVENT IS RELATED TO THE EXTENT OF REACTION. AS THE REACTION PROCEEDS, PART OF THE REACTION PRODUCT IS CONTINUALLY MIXED WITH A SOLVENT AND FLOWED THROUGH A TRANSLUCENT CELL MOUNTED BETWEEN A LIGHT SOURCE AND A PHOTOELECTRIC CELL. THE TEMPERATURE OF THE SAMPLE IN THE CELL IS EITHER MAINTAINED CONSTANT DURING THE REACTION OR IS MAINTAINED AT THE CHANGING MISCIBILITY TEMPERATURE DURING THE REACTION BY SIGNALS FROM THE PHOTOELECTRIC CELL TRANSMITTED TO A TEMPERATURE CONTROLLER, AND IS PARTICULARLY ADAPTED TO THE OXYLATION OF ALIPHATIC ALCOHOLS, ALKYLPHENOLS, AND FATTY ACIDS.

y R. G. BRUCE 3,592,607

APPARATUS FOR CONTINUOUSLY MONITORING THE .E w PROCESS OF CERTAINREACTIONS Original Filed March 8, 1966 3 Sheets-Sheet l j 5 J SAMPLE 32DISCHARGE \0 L] \40 i 20 3o SOLVENT REACTION PRODUCT SAMPLE 4 ODISCHARGE I 4o 2o 22\ I 36 30 l2 l8 INVENTOR. l I RONALD G. sauceSOLVENT REACTION BY PRODUCT A m ATTORNEY July 13, 1971 R. a. sauce.

APPARATUS FOR GONTINUOUSLY MONITORING THE rnocnss OF CERTAIN REACTIONSOriginal Filed March 2. 1966 3 Sheets-Sheet 2 FIG. 4

FIG. 3

I D U 0 L C l mono 5 umnhx 1 4 I213 k nzzmk AVERAGE OF THE REACTEDMATERIAL FIG. 5

INVENTOR. 5. BR U C E RONALD ATTORNEY July 13, 1971 R. G. sauce3,592,601

APPARATUS FOR CONTINUOUSLY MONITORING THE PROCESS OF CERTAIN REACTIONSOriginal Filed March 2, 1966 3 Sheets-Sheet I CLOUDY CLEAR MOLES OFETHYLENE OXIDE (OR TIME) INVENTUR. RONALD G. BRUCE ATTORNEY UnitedStates Patent Oflice Patented July 13, 1971 US. Cl. 23-253 2 ClaimsABSTRACT OF THE DISCLOSURE Apparatus for determining the progress of areaction between reactants which produce a product whose miscibility ina solvent is related to the extent of reaction. As the reactionproceeds, part of the reaction product is continually mixed with asolvent and flowed through a translucent cell. mounted between a lightsource and a photoelectric cell. The temperature of the sample in thecell is either maintained constant during the reaction or is maintainedat the changing miscibility temperature during the reaction by signalsfrom the photoelectric cell transmitted to a temperature controller, andis particularly adapted to the oxylation of aliphatic alcohols,alkylphenols, and fatty acids.

DISCLOSURE Cross-references to related applications This application isa divisional application of my copending application entitled Method andApparatus for Continuously Monitoring the Progress of Certain Reactions,Ser. No. 684,578, filed Sept. 25, 1967 (now U.S. Pat. 3,478,111 issuedNov. 11, 1969), which in turn was a continuation of my then copendingapplication entitled Method and Apparatus for Continuously Monitoringthe Progress of Certain Reactions, Ser. No. 531,084, filed Mar. 2, 1966,now abandoned, which in turn was a continuation-in-part of myapplication entitled Method and Apparatus for Continuously Monitoringthe Progress of Certain Reactions, Ser. No. 180,682, filed Mar. 19,1962, now abandoned.

Background This invention relates to apparatus for continuouslymonitoring the progress of certain chemical reactions and forautomatically determining when certain types of addition reactions haveproceeded to a desired end point. More particularly, but not by way oflimitation, the present invention relates to novel apparatus which maybe used to determine when a desired number of moles of an alkylene oxidehave been added to compounds of certain types to produce alkylene oxideadducts having an optimum number of ether groups in each moleculethereof.

It is known that the products of some chemical reactions will vary inthe extent to which they are miscible with a solvent according to theextent to which certain functional groups derived from one of thereactants has been incorporated in, or added to, the second reactant toyield the reaction product. Stated differently, in some types ofchemical reactions, the number of moles of one reactant which hasentered into the reaction by combining with, or adding to, but a singlemole of a second reactant is directly related to the miscibility in oneor more solvents of the product produced by the reaction. As examples ofsuch reactions may be cited the reactions of alkylene oxides (orepoxides), particularly ethylene oxide and propylene oxide, with water,alkyl phenols, aliphatic polyhydric and monohydric alcohols(particularly the fatty alcohols), and fatty acids. In the latter threeinstances, the reactions may be expressed, respectively, by thefollowing equations when ethylene oxide is the alkylene oxide employed:

In each of reactions (a), (b) and (c), R is an aliphatic radical and pis the number of moles of ethylene oxide which is added to the alcohol,phenol and fatty acid reactants. In each instance, the magnitude of pwill depend upon the extent to which the reaction has been allowed toproceed. The miscibility of the products with water is related to thenumber of ethoxy groups incorporated therein.

Other types of reactions which yield a product which varies in itsmiscibility with water according to the extent which the reaction hasproceeded are those reactions by which sulfonyl groups (SO are added tothe product to yield various types of sulfonic adducts. Yet other typesof reactions by which products are yielded which vary in theirmiscibility with one or more solvents according to the extent to whichthe reaction has continued will be recalled by those skilled in the art.

It is frequently of considerable importance to know the extent to whichreactions of the above-discussed types have proceeded. For example, eachof the ethylene oxide reactions set forth in equation form above may beutilized to produce ethoxylated products having substantial utility asdetergents. These ethoxylated products show a negative solubilitycoefiicient in aqueous solution, especially if the degree ofethoxylation is low (where p is about 6 or less). This causes emulsionscontaining such products to become increasingly unstable with increasingtemperatures. Other important properties, such as freeze point, sudsingability, and dermatological mildness, are also closely related to thenumber of moles of ethylene oxide which is reacted, and which enterseach of the products as an ethoxy group. In order to obtain the degreeof product quality control which is required, it is thus necessary to insome manner be constantly apprised of the number of ethoxy groups whichhas been incorporated in the product.

One of the methods "which has previously been employed for determiningthe number (p) of certain functional groups which have been incorporatedin a particular product of the type described consists of periodicallytaking samples of the product, mixing the product with a suitablesolvent, and observing the cloud point in each of the mixtures. Thecloud point, of course, may be defined as the temperature at which amiscible mixture of the product with a certain solvent suddenly becomesan immiscible mixture. In the case of the reaction of ethylene oxidewith aliphatic alcohols to produce aliphatic ethoxylated alcohols,samples of the ethoxylated product are periodically taken and are eachadded to water in the ratio of about 1 percent of product to 99 percentof water. Each sample is then heated until it suddenly becomes cloudy orimmiscible. The temperature (cloud point) is noted. Each cloud point isdirectly related to the number of ethoxy groups which has beenincorporated in the product, so that when a desired num- 3 her of etherfunctional groups characterizes the product, a specific cloud point maybe observed for the product.

Several disadvantages characterize the described method of determiningwhen the desired end point of an epoxylation reaction has been reached.In the first place, it is laborious and time-consuming to take a seriesof samples of the reaction product and transport them to the laboratoryfor cloud point determinations. Also, a plurality of personnel includingsample carriers and testers or chemists are required. A more importantdisadvantage, however, is the difiiculty of correlating the observedcloud points with the extent to which the reaction has proceeded. Thisis because of the time lag which necessarily must occur between the timeof sampling and the time of cloud point observation. By the time thecloud point corresponding to the desired product characteristic has beenobserved, the product has changed, and a greater number of epoxy groupshas been incorporated in the product than desired. Only byextrapolation, with its attendant inherent errors, can this overshootingbe avoided.

A major object of the present invention is to provide apparatus whichautomatically indicates when a desired reaction end point has beenreached in those reactions which result in the sequential incorporationof a varying number of miscibility-affecting functional groups in thereaction product.

A further object of the present invention is to provide relativelyinexpensive apparatus for monitoring the cloud point of a mixture ofliquids in order to determine when a particular cloud point occurs as aresult of variation in the chemical composition of one of the mixtureconstituents.

Another object of the invention is toprovide an automatic cloudpointdetermining apparatus which is novelly adapted for use indetermining the extent to which certain chemical reactions must proceedin order for the miscibility of the reaction product to reach a givenvalue.

A further object of the invention is to provide an apparatus forautomatically controlling the duration of a chemical reaction in whichthe miscibility of the reaction product in a solvent depends upon theextent to which the reaction has proceeded.

Another object of the present invention is to provide apparatus forautomatically permitting only an optimum number of moles of ethyleneoxide to react with a dihydric or monohydric aliphatic alcohol accordingto the desired properties of the reaction product.

Yet another object of the present invention is to provide aninexpensive, yet durable, apparatus for automatically indicating by acloud point determination, when certain types of reactions have reacheda desired end point.

Other objects and advantages of the invention will become apparent upona further reading of the following detailed description of the inventionin conjunction with a perusal of the accompanying drawings whichillustrate my invention.

Summary of the invention In one of its broader aspects, the presentinvention comprises automatically and continuously mixing a sample ofthe reaction product (which is continuously bled from the reactionchamber) in a constant predetermined proportion with a solvent in whichthe reaction product displays a cloud point when mixed in thatpredetermined proportion. Preferably, the proportion of reaction productto solvent is selected so that the cloud point which will characterizethe mixture as to the number of miscibility-affecting functional groupsin the product is within a range of conveniently attained and easilymaintained temperatures. After the product and solvent are mixed, themixture is continuously circulated through a conduit which passesthrough a controlled temperature chamber to a photoelectric testingsystem disposed within the chamber. Depending upon the manner in whichthe method is to be practiced, the temperature of the temperaturechamber either is maintained constant or is increased steadily duringthe course of monitoring. The photoelectric testing system consists ofthe usual photoelectric cell, source of electromagnetic radiation, andsample cell positioned between the latter two elements. For a morecomplete understanding of systems of this type, the reader is referredto US Pat. 2,498,941 and German Pat. 666,557.

As the sample consisting of the product-solvent mixture flows throughthe controlled temperature chamber toward the sample cell, itstemperature is altered to that prevailing in the chamber. As the sampleenters the sample cell, it will be either a miscible or immisciblemixture, depending upon whether the reaction has proceeded beyond or,alternatively, has not yet reached a point where addition compoundscontaining sufficient miscibility-affecting functional groups have beenformed to render the mixture immiscible at the temperature prevailing inthe chamber. Depending upon its state of miscibility, theproduct-solvent mixture will attenuate the light beam passingtherethrough to a lesser or greater extent, which will in turn bereflected by the output from the photoelectric cell.

In one embodiment of the invention, the chamber temperature is presetand maintained at a value that corresponds to the cloud pointtemperature of the sample mixture when the reaction product has thedesired number of miscibility-affecting functional groups incorporatedtherein. Thus, as the sample enters the sample cell, it will haveattained this preset temperature, and will be either a miscible orimmiscible mixture, depending upon whether the reaction has proceededbeyond, or alternatively, has not yet reached the desired end point. Bycommencing the flow of the sample mixture simultaneously with, orshortly after, the commencement of the reaction, the incorporation ofthe predetermined desired number of miscibility affecting functionalgroups in the reaction product will be evidenced by a relatively sharpchange in the sample mixture from a state of miscibility to a state ofimmiscibility, or vice versa. This change in turn is reflected by achange in the output from the photoelectric cell. The signal from thephotoelectric cell may be utilized to drive a recorder, or to operateappropriate process control instruments to interrupt or stop thereaction. In this embodiment, the number of miscibility-affectingfunctional groups incorporated in the reaction product is not indicatedat any time prior to the point where a maximum desired number of groupshas been added.

In another embodiment of the invention, the chamber temperature iscontinually increased to maintain a temperature corresponding to thecloud point temperature of the mixture currently passing through thesample chamber. At the beginning of the reaction, the mixture ofreaction product and solvent flowing through the sample cell will have aminimum cloud point temperature. As the reaction continues, the cloudpoint temperature will continuously increase and the temperature in thetemperature chamber is automatically increased to correspond with thiscloud point temperature. This is brought about by utilizing the outputfrom the photoelectric cell, which determines the state of miscibilityof the mixture, to regulate through intermediate means the temperaturewithin the temperature chamber. At any time, then, the progress of thereaction is shown by the cloud point or miscibility temperatureprevailing in the temperature chamber. The signal generated by atemperature indicator can be utilized to drive a recorder or to operateappropriate process control instruments to interrupt or stop thereaction.

DESCRIPTION OF THE DRAWINGS In order to more completely describe theinvention in its various aspects, reference is had to the followingdrawings of which:

FIG. 1 is a schematic view illustrating one embodiment of the apparatuswhich is utilized in practicing the method of the present invention.

FIG. 2 is a schematic view illustrating a second embodiment of theapparatus which is utilized in practicing the method of the presentinvention.

FIGS. 3 and 4 are detailed views of the sample cell which is utilized inthe apparatus of the invention.

FIG. 5 is a graph illustrating the relationship between the number ofmoles of alkylene oxide which is reacted in one of the heretoforedescribed reactions, and the cloud point of the reaction product.

FIG. 6 is a drawing illustrating the trace which is obtained upon therecording device of the apparatus as the reaction proceeds through adesired end point.

Detailed description Referring now to the drawings in detail, andparticularly to FIG. 1, reference character 10 designates aproportioning pump or other suitable mixing device which may be utilizedfor mixing two liquids in a predetermined proportion. For a betterunderstanding of the structure and operation of a proportioning pump,the reader may refer to Lindsay United States Patent 2,656,845.Reference characters 12 and 14 designate conduits for conducting asolvent and reaction product, respectively, to the propor tioning pump10 from the solvent source and the reactor (not shown). Referencecharacters 16 and 18 designate conduits for discharging the solvent andreaction product, respectively, to the common mixing coupling 20.Conduit 22 connects to the discharge end of coupling 20, passes intocontrolled temperature chamber 24, coils into a plurality ofconvolutions 30, and connects with sample cell 32, which is positionedbetween an incandescent lamp 34, or other suitable source ofelectromagnetic radiation, and a photoelectric cell 36. Dischargeconduit 38 connects to the opposite side of the sample cell 32. Suitableheating elements 26 are connected to a temperature control device 28,such as a thermostat, which permits the temperature within thecontrolled temperature chamber 24 to be altered as desired. Electricalleads 40 connect the photoelectric cell 36 to various types of meters,and to suitable control devices, such as that represented by referencecharacter 43 in FIG. 1, for controlling the reaction to terminate it atany desired end point if the use of such devices is desired. A recorder42 can also be connected by electrical leads in order to permit thecurrent generated by the photoelectric cell to be registered in the formof visible indicia upon the recorder chart.

In FIG. 2, a second embodiment of the apparatus is presented. Referencecharacters 10 to 24, and to 38 designate portions of the apparatusidentical to those of FIG. I. In this embodiment, however, electricalleads 40 connect the photoelectric cell 36 to a heater controller whichis controlled by signals from the photoelectric cell 36 and which, inturn, is connected to and controls the heating element 26. A change inthe signal from the photoelectric cell 36 to the heater controller 60 isreflected by a decrease or increase in the electrical energy supplied tothe heating elements 26, which in turn causes the temperature in thecontrolled temperature chamber to rise or fall. A thermocouple or othertemperature indicating device 62 is mounted within the controlledtemperature chamber and is connected by electrical leads 66 to varioustypes of control meters such as designated by reference character 68 inFIG. 2 for controlling the reaction to terminate it at any desired cloudpoint if the use of such devices is desired. A recorder 64 can also beconnected by electrical leads in order to permit the current generatedby the thermocouple 62 to be registered in the form of visible indiciaupon the recorder chart.

The construction of the sample cell 32 which is utilized in theapparatus of the invention may be best understood by reference to FIGS.3 and 4. As illustrated in these figures, the sample cell comprises anannular, disc-shaped block 44 having an axial bore 46 therethrough, andprovided with a pair of radial passageways 48 communicating with theaxial bore and provided for the purpose of permitting the sample line 22and discharge line 38 to be iii connected to the sample cell. Theannular block 44 has a pair of opposed transparent, parallel faces 50which form a pair of cell Windows and are held on said block by screws54 or other suitable fastening elements.

Before commencing a description of the operation of the first-describedembodiment of the apparatus of the present invention, it is thought thatit would be useful in imparting a better understanding of the inventionto explain in greater detail the basic principle upon which theinvention is bottomed. A typical reaction of the type which haspreviously been described, and which may be utilized in explaining suchprinciple, is the reaction of ethylene oxide with an aliphaticmonohydric alcohol to produce an ethoxylated aliphatic alcohol. Thepostulated reaction may be represented by the following equation:

Where m defines the length of the aliphatic monohydric alcohol used asone of the reactants, and p is the number of moles of ethylene oxidewhich is added to the alcohol and enters the product as ethoxy groups.Alcohol ethylene oxide reactions of this general type are described ingreater detail in Carter, US. Pat. 2,870,220. Products of this type havea variety of uses, and in many instances such uses will depend upon aspecific value or range of values of the number of ethoxy groups whichare incorporated in the product. Thus, in order to satisfy therequirernents of a particular customer with respect to the extent ofethoxylation of the product, the manufacturer of the ethoxylatcd alcoholmust be constantly apprised of the number of moles of ethylene oxidewhich has reacted with the aliphatic alcohol in order that he mayterminate the reaction at the desired point.

As illustrated by the graph shown in FIG. 5, for a given mixture ofreaction product and a solvent, such as water, a correlation betweencloud point and the number of epoxy groups in the product exists, andmay be shown by plotting the cloud point against the average p of theproduct. It is known in advance of the cloud point tests which specificcloud point corresponds, for a particular product-solvent mixture, to aspecific number of moles of alkylene oxide which has reacted and whichappears in the product as the same number of epoxy groups. Thus, whenany sample of product displays the particular cloud point whichcorresponds to a predetermined number of moles of alkylene oxide whichhas entered into the reaction, the reaction can be terminated so thatthe product yielded does not contain an excessive number of epoxygroups.

By the apparatus of the present invention, the disadvantages which havecharacterized the previous method of determining the end point ofreactions by which miscibility-affecting groups are incorporated in thereaction product have been overcome, and a considerably more economicaland accurate method for attaining this control is contemplated. In thefirst embodiment of the apparatus (FIG. 1), a small portion of thereaction product is continuously bled from the reactor and passed intothe proportioning pump 10 through the conduit 14. Simultaneously, asuitable solvent in which the reaction product is miscible, at least incertain proportions, is charged to the proportioning pump through asecond conduit 12. The proportioniug pump 10 is adjusted so that itsoutput of reaction product and solvent through the conduits 18 and 16,respectively, is such as to give a mixture of predetermined proportionswhen these materials are mixed in the mixing valve 20. For example, whenthe aliphatic alcoholethylene oxide reaction discussed above is thereaction of concern, the proportions in the mixture which is producedmay range between 1 percent of the product in 99 percent of water to 25percent of product in percent of water.

After the product and solvent are mixed in the mixing valve 20, themixture is passed thrOugh the sample line 22 into the controlledtemperature chamber 24 where the sample mixture is heated to thetemperature of the chamber as it passes through the convolutions 30. Thetemperature of the controlled temperature chamber 24 has previously beenadjusted to a temperature equal to the cloud point which characterizesthe sample system when the reaction product includes a desired number ofmiscibility-affecting functional groups. Thus, prior to the time thesample mixture is introduced to the sample cell 32, the sample hasattained a temperature at which the miscibility of its components willchange more or less drastically when the reaction has reached a stagesuch that the desired number of miscibility-affecting functional groupshave been incorporated into the reaction product. The process ofbleeding a portion of the reaction product from the reactor and passingit through the apparatus of the present invention will, of course, havebeen commenced at the time the reaction is commenced, or shortlythereafter, so that there is no danger of overshooting or bypassing thereaction end point which it is the function of the incandescent lamp 34and photoelectric cell 36 to observe.

In the early stages of the reaction, the solvent and reaction productwill be either immiscible and therefore characterized by a cloudyappearance, or will be miscible and clear. In the case of thealcohol-ethylene oxide reaction, the mixture is initially immiscible andcloudy. The

degree of miscibility of the reaction product in water increases as thenumber of ethoxy groups incorporated in the product is increased. As themixture of product and solvent approaches miscibility as a result of thefurther inclusion of miscibility-affecting functional groups in theproduct, the mixture approaches a cloud point corresponding to thetemperature of the controlled temperature chamber 24 and also, ofcourse, of the photoelectric detecting unit enclosed in the chamber.

At the instant when the predetermined desired number ofmiscibility-affecting functional groups is incorporated in the reactionproduct, the previously immiscible sample system will undergo arelatively drastic change in the miscibility of its components. Thiswill result in a sharp increase in the amount of light or otherelectromagnetic radiation which is passed by the sample in the samplecell 32 and which impinges upon the photoelectric cell 36. The sharpchange in the intensity of radiation acting upon the photoelectric cell36 will in turn be reflected by a clearly discernible change in movementof the pen of the recorder 42. The output signal from the photoelectriccell 36 may also be utilized to operate control equipment of anysuitable type for shutting off the flow of ethylene oxide to the reactorand thus terminating the reaction, dumping the finished batch ofreaction product, or any other control function which may be desired.After passing out of the sample cell 32 in the discharge line 38, thesample may be disposed of in any suitable manner.

As a further example of the manner in which the invention functions, theattention of the reader is invited to FIG. 6 of the accompanyingdrawings which shows a typical trace developed by a continuous recordinginstrument in response to the output from the photoelectric cell 36 whena sample of ethoxylated aliphatic alcohol in water was passed throughthe sample cell 32. The proportion of ethoxylated product to water was 1to 99, or in other words, a 1% aqueous solution of the reaction product.The temperature within the controlled temperature chamber 24 wasadjusted to 58 C., the temperature corresponding to the cloud point ofan ethoxylated aliphatic alcohol containing an average of 8.6 ethoxygroups in each mole of product. The trace commences at the lower leftcorner of the chart as a product resulting from the reaction of anaverage of 7.15 moles of ethylene oxide with each mole of alcohol ispassed through the sample cell. As the reaction proceeded, no deflectionof the recorder pen occurred when 7.5 moles of ethylene oxide hadreacted with the alcohol. However, when 8.6 moles of the ethylene oxidehad reacted, a pen deflection corresponding to 6 millivolts was noted.When 10.2 moles of ethylene oxide had reacted, a further deflection ofthe pen of 6 millivolts occurred. After this, no further pen deflectionwas produced by further reaction of the ethylene oxide.

From the recorder chart shown in FIG. 6, it will be noted that a totalpen deflection of 12 millivolts was produced by a diflerence of 2.7moles of ethylene oxide reacted. The instrument thus may be said todisplay a sensitivity of about 4.5 millivolts per mole. It may be seenthat the extent of reaction may be easily determined from an observationof the recorder trace.

In the second embodiment of the apparatus (FIG. 2), the signal from thephotoelectric cell is utilized to maintain the temperature of thetemperature chamber to correspond with the cloud point temperature ofthe mixture passing through the sample cell.

The flow of solvent, reaction product, and sample mixture of the two isidentical to that in FIG. 1. In passing through the convolutions 30, thesample mixture is heated to the temperature of the chamber. Thetemperature of the controlled temperature chamber 24 is equal, or nearlyso, to the current cloud point temperature of the sample mixture passingthrough the sample cell 32 by virtue of the control action of thephotoelectric cell output signal. When the output from the photoelectriccell to the heater controller 60 indicates the presence of a cloud pointin the sample mixture passing through the sample cell, the heatercontroller causes less electrical current to be supplied to the heater26 to decrease the temperature in the temperature chamber and,correspondingly, the temperature of the sample mixture passing throughthe convolutions 30. Thus, the temperature in the controlled temperaturechamber is always equal, or nearly so, to the cloud point temperature ofthe sample mixture in the sample cell. The progress of the reaction isthus always apparent by comparing the cloud point temperature of thesample mixture as shown by thermocouple 62 with a previous correlationof cloud point temperature with extent of reaction.

The heater controller 60 may take the form in which the signal from thephotocell 36 is transmitted through a current converter (Foxboro 693,for example) and to a primary controller (Foxboro M/62, for example);simultaneously the output from the thermocouple 62 is transmitted by anelectrical lead (not shown) through a current converter (Foxboro 693,for example) to a cascade controller (Foxboro M/67SRG2 with controller,for example); the difference in signals between the output from theprimary controller and the current converter attached to thethermocouple 62 as measured by the cascade converter are then passedthrough a control device to a current regulator (such as a saturablecore) device to increase or decrease the current supplied to the heater26.

The output from the thermocouple 62 or from a current converter ispassed through electrical lead 66 to a recorder 64 in order to permitthe current generated by the thermocouple 62 to be registered in theform of visible indieia upon the recorder chart. The output from thethermocouple 62 or a current converter can also be directed to varioustypes of meters and to suitable control devices such as that representedby reference character 68 for controlling the reaction to terminate thereaction at any desired end point as preferred.

The following examples are presented in further illustration of theinvention.

Example 1.-A mixture of of aliphatic straight chain alcohols averaging43 percent C 30 percent C 20 percent C and 12 percent C is reacted withethylene oxide. It is desired to conduct the reaction to a point where8.6 moles of ethylene oxide per mole of alcohol is incorporated in thereaction product. The cloud point of a mixture of 1 volume of thedesired reaction product in 99 volumes of water is previously determinedto be 58 C. From a reaction chamber in which the alcohol mixture andethylene oxide are reacted over a period of time, a sample stream of thereaction product is continually withdrawn. This sample stream iscontinually mixed with water in a ratio of 1 volume of reaction productto 99 volumes of water. This mixture of water and reaction product isthen continually circulated through a temperature zone maintained at 58(3., the temperature, as just stated, corresponding to the cloud pointof the ethoxylated alcohol product desired. While maintained at the 58C. temperature, the mixture is then circulated through a photoelectricsystem which measures the turbidity or state of miscibility of themixture. As the reaction continues, turbidity of the sample stream isindicated by the photoelectric cell when 7.5 moles of ethylene oxide hasbeen reacted with the alcohol. However, when 8.6 moles of the ethyleneoxide has reacted, the photoelectric cell begins indicating the presenceof a miscible mixture and continues to increasingly indicate a conditionof miscibility. The reaction of the ethylene oxide with the alcohol isstopped shortly thereafter.

Example 2.A sample stream of reaction product is continually withdrawnfrom a reaction chamber in which the same kind of alcohol mixture andethylene oxide as in Example 1 is reacted over a period of time.Withdrawal of the sample stream is begun at the start of the reaction.It is desired to continually monitor the course and extent of thereaction in progress. The sample stream is continually mixed with waterin a ratio of one volume of sample to 99 volumes of water. Again, it isdesired to react the alcohol and ethylene oxide so that about 8.6 molesof ethylene oxide are added per mole of alcohol. This again correspondsto a cloud point temperature of about 58 C. of the reactionproduct-water mixture. This mixture of water and reaction product isthen circulated through a temperature zone initially at a temperature of30 C., so that the sample mixture is brought to this temperature of 30C. The mixture, originally in a state of complete immiscibility, iscontinually circulated through a photoelectric cell wherein itsturbidity or state of miscibility is determined. As the reactionproceeds, sufiicient moles of ethylene oxide are incorporated in thereaction product to render the mixture miscible. When the photoelectriccell indicates this condition of transition between immiscibility andmiscibility, the temperature in the temperature zone is increasedslightly so that the mixture reverts to its original immiscible state.As the reaction between alcohol and ethylene oxide continues and themixture of water and reaction product is circulated through thetemperature zone and photoelectric cell, the cloud point temperature ofthe mixture continually increases. The temperature in the temperaturezone is continually increased to maintain the mixture just at thethreshold of the cloud point, as shown by the photoelectric cell. Whenthe cloud point temperature reaches 58 0., the reaction has proceeded toa point where about 8.6 moles of ethylene oxide have been added per moleof alcohol and the reaction is stopped.

From the foregoing description of the invention, it will be appreciatedthat a relatively inexpensive apparatus for rapidly and constantlymonitoring certain types of reactions has been proposed. The inventioneliminates the time lag between observation of cloud point and reactionproduct sampling which has previously been characteristic of the methodsused in monitoring and controlling such reactions.

Although reference has been made herein to certain preferred embodimentsof the invention, it is to be understood that these are described by wayof example and illustration only. Accordingly, it is contemplated that10 modifications and variations can be made in the operating techniquesdescribed without departing from the true spirit and scope of theinvention.

What is claimed is:

1. A system for monitoring an addition reaction between an alkyleneoxide compound and an aliphatic alcohol to produce an addition compoundcontaining a desired average number of molecules of said alkylene oxidecompound added to each molecule of aliphatic alcohol, said desiredaverage number increasing with length of reaction time and said additioncompound when mixed with a solvent displaying a cloud point indicativeof the average number of molecules of said alkylene oxide compound addedto each molecule of said aliphatic alcohol, said system comprising:

(a) a liquid proportioning pump into which said reagents are introducedfor releasing therefrom in predetermined proportions;

(b) a mixing coupling for combining said reagents to give a mixture ofpredetermined proportions;

(c) a conduit connecting said proportioning pump and said mixingcoupling for the passage of said reagents;

(d) a hollow temperature chamber for heating said mixture of reagents toa desired temperature;

(e) heating elements in said temperature chamber for bringing thetemperature therein to a desired degree;

(f) a temperature control device connected to said heating elements tomanipulate the output of said heating elements thereby determining thetemperature within said temperature chamber;

(g) a convoluted conduit in said temperature chamber through which saidmixture of reagents is passed to make the temperature of said mixturecorrespond to the temperature of said chamber;

(h) a conduit connecting said convoluted conduit and said mixingcoupling for the passage of said mixture of reagents;

(i) a photoelectric cell positioned in said temperature chamber so as toreceive a beam of light after passage thereof through said mixture ofreagents;

(j) a light source positioned opposite said photoelectric cell in saidtemperature chamber so as to interact therewith by emanating a beam oflight which passes through said mixture of reagents and is received bysaid photoelectric cell to determine the degree of miscibility of saidsaid mixture at a given point of the reaction;

(k) a sample cell in said temperature chamber positioned between saidphotoelectric cell and said source of light so as to allow a light beamemanating from said light source to pass through said mixture ofreagents contained therein, and be recorded by said photoelectric cells,said sample cell comprising a cylindrical block having an axial boretherethrough for the containment of said mixture and having a pair ofradial passageways therethrough oommunicating with the axial bore forthe passage of said mix ture therethrough, and a pair of opposed,transparent parallel faces secured to the opposite sides of saidcylindrical block and covering the axial bore therethrough at each endof said bore so as to permit the transmittal of a light beam emanatingfrom said light source through said mixture contained in said axialbore;

(1) a conduit connected to the radial passageways in said block and tosaid convoluted conduit for the passage of said mixture; and

(m) a recording device connected to said photoelectric cell to permitcurrent generated by the receipt of said light beam passing through saidmixture by said photoelectric cell to be registered in the form ofvisible indicia upon a recorder chart.

11 12 2. The system of claim 1 wherein said temperature 2,792,484 5/1957Gurewitseh et a1. 219-502 control device of (f) is also connected to theoutput of 3 165 929 1/ 1965 Pelavin 23 253 said photoelectric cell; andthere is substituted for said recording device of (111) connected tosaid photoelectric MORRIS 0, WQLK, P i E i cell (i) a recording deviceconnected to said temperature 5 R M REESE Assistant Examiner chamber(d).

References Cited US Cl. X R

UNITED STATES PATENTS 23 230; 219 502; 250 21 1,960,615 5/1934 Baker23-230A 10 2,498,941 2/1950 Clardy 2502l8X

